| 摘要 |
<p>Squirrel-cage rotors are made for alternating electric machines by the low-pressure casting process, so both the grooves and the short-circuit rings are accurately cast. The novelty is that a preheated stack of laminations is inserted between an upper and a lower die in a press, and a mandrel is fed through the vertical hole in the stack; the lower die has an ingate above a vertical standpipe fed with molten metal from a crucible located below the press in an air-tight holding furnace. A pressurised gas is fed into the crucible to drive the metal up the standpipe and into the dies, while the stack of laminations is subjected to the action of a vibrator which improves the soundness of the casting. Relatively long rotors can be cast with a narrow grooves without air being entrapped in the groovs during casting. The air can cause piping or porosity, resulting in scrap castings.</p> |
